ISIS flapping

[christof32]

Hello everybody.

I have a rather random problem with ISIS which happened twice in the last month in my 7513 p-router.

ISIS was flapping in two different interfaces of the same router simultaneously. Here is the output of the log:

Jul 15 15:01:42.976: %CLNS-5-ADJCHANGE: ISIS: Adjacency to xxx (GigabitEthernet8/0/0) Down, hold time expired

Jul 15 15:01:47.728: %CLNS-5-ADJCHANGE: ISIS: Adjacency to yyy (FastEthernet4/0/0) Down, hold time expired

Jul 15 15:01:47.964: %CLNS-5-ADJCHANGE: ISIS: Adjacency to xxx (GigabitEthernet8/0/0) Up, new adjacency

Jul 15 15:01:51.912: %CLNS-5-ADJCHANGE: ISIS: Adjacency to yyy (FastEthernet4/0/0) Up, new adjacency

Jul 15 15:01:57.964: %CLNS-5-ADJCHANGE: ISIS: Adjacency to xxx (GigabitEthernet8/0/0) Down, hold time expired

Jul 15 15:02:01.912: %CLNS-5-ADJCHANGE: ISIS: Adjacency to yyy (FastEthernet4/0/0) Down, hold time expired

Jul 15 15:02:05.512: %CLNS-5-ADJCHANGE: ISIS: Adjacency to yyy (FastEthernet4/0/0) Up, new adjacency

The only way for the Router to stop doing that, was to shut/no shut one of the affected interfaces!!!

Do you thing that it might be a bug ?

Have you ever met something like that?

Please help!!!

[Peter Paluch]

Hello,

Are there any errors detected on the interface? Check the show interface Gi8/0/0 and show interface Fa4/0/0 output. Were there any other logs recorded that could be related to this flapping?

Also, what were the logs recorded on the neighboring routers to Gi8/0/0 and Fa4/0/0? Did they record the same incident?

Are you using any QoS mechanisms on the interfaces? The IS-IS traffic is a non-IP traffic which may be troublesome if the interfaces are oversubscribed.

Looking forward to hearing from you.

Best regards,

Peter